The use of water-in-oil emulsions was recently adapted to biological applications by several groups aiming at improving enzymes by directed evolution, SNP analysis on streptavidin coated beads, and DNA sequencing. Dressman et al., “Transforming single DNA molecules into fluorescent magnetic particles for detection and enumeration of genetic variations” Proc Natl Acad Sci USA, 100:8817-8822 (2003); Ghadessy et al., “Directed evolution of polymerase function by compartmentalized self replication” Proc Natl Acad Sci USA 98:4552-4557 (2001); Tawfik et al., “Man-made cell-like compartments for molecular evolution” 16:652-656 (1998); Margulies et al., “Genome sequencing in microfabricated high-density picoliter reactors” Nature 437:376-80 (2005); and Shendure et al., “Accurate multiplex polony sequencing of an evolved bacterial genome” Science 309:1728-1732 (2005).
Unfortunately, the emulsion techniques are slow and cumbersome. As a result, they are not ideal for commercial applications.